An ADU builder in San Antonio is a licensed contractor who designs and constructs accessory dwelling units — detached backyard units, garage conversions, attached additions, and junior ADUs (JADUs). Because an ADU is a complete second dwelling, the builder coordinates foundation, framing, plumbing, electrical, and HVAC work and pulls it through San Antonio's permit process and utility connections. Not every general contractor has built one, so the right builder is one with ADU-specific experience in Texas.
What ADU Builders Cost in San Antonio [10][11][12][13]
Based on our San Antonio cost data, expect the following ranges from local ADU builders. Quotes for the same scope typically vary 20-40% between contractors, so getting at least three bids is the single best way to control cost.
| New Detached ADU (all-in) | $125,000-$320,000 |
| Cost per Sq Ft | $225-$400 |
| Garage Conversion | $30,000-$90,000 |
| Prefab / Modular ADU (installed) | $150,000-$300,000 |
| City Permit & Plan Review | FY2026 DSD fee schedule (rev. Oct 2025), new residential construction by size: $988 total basic permit fees for 501-1,000 sq ft, $1,022 for 1,001-1,250 and $1,201 for 1,251-1,500 sq ft (building, trade and sewer permits plus a $200 plan review). 100% waivable for income-qualified ADUs. |
| Impact Fees | The City itself charges no impact fee. SAWS water and wastewater impact fees (effective July 1, 2024; about $7,300-$12,000 per EDU combined, by service area) apply only if the ADU adds service beyond the lot's platted EDU, e.g. a separate meter; waivable for income-qualified ADUs under the Fee Waiver Program. |
For a full line-item breakdown, see our San Antonio ADU cost guide. To confirm what you're allowed to build before you hire, review the San Antonio ADU rules (max detached size: The larger of 800 sq ft gross floor area or 50% of the main house's gross floor area, capped at 1,600 sq ft (UDC 35-371; IB 402 FAQ 1). Every lot may therefore have an ADU of at least 800 sq ft regardless of the size of the main house.; owner-occupancy: Required. The owner must occupy either the main house or the ADU as a permanent residence, sign a notarized affidavit, and record a covenant with the Bexar County Clerk before the permit issues; the owner-occupied unit may never be rented (UDC 35-371(a)(1); IB 402 Attachment B). Enforcement uses voter registration, homestead and driver's-license records and cross-checks against STR permits.).
Get Free ADU Quotes in San Antonio
Tell us about your project and we'll pass it to ADU builders serving San Antonio. Free, no obligation — you choose who to work with. We don't have builders in every area yet; if nobody covers yours, we'll email you to say so.
Takes about a minute.
Up to 5 independent local ADU builders — never more, and we tell them nothing you don't submit here.
Compare quotes, verify license & insurance, hire (or don't). No spam either way.
🔒 Your info is secure. We share it only with contractors quoting your project. No spam, no obligation.
Just browsing? Search ADU builders near you by ZIP code.
How to Vet an ADU Builder in San Antonio
- License: Confirm a current contractor's license in Texas and that it's in good standing. Ask for the license number and verify it with the state board.
- ADU-specific experience: Ask how many ADUs they've completed in or near San Antonio and request addresses or photos. ADU permitting and setbacks differ from a kitchen remodel.
- Portfolio & references: Get references from recent ADU clients and, if possible, visit a finished unit.
- Insurance: Verify general liability and workers' compensation coverage. Ask for a certificate of insurance.
- Written, detailed bid: Insist on an itemized, fixed-price or clearly-scoped bid — not a verbal estimate. It should state whether permits (FY2026 DSD fee schedule (rev. Oct 2025), new residential construction by size: $988 total basic permit fees for 501-1,000 sq ft, $1,022 for 1,001-1,250 and $1,201 for 1,251-1,500 sq ft (building, trade and sewer permits plus a $200 plan review). 100% waivable for income-qualified ADUs.), plan check (Up to 3 business days to first redline comments (DSD ADU page)), and impact fees (The City itself charges no impact fee. SAWS water and wastewater impact fees (effective July 1, 2024; about $7,300-$12,000 per EDU combined, by service area) apply only if the ADU adds service beyond the lot's platted EDU, e.g. a separate meter; waivable for income-qualified ADUs under the Fee Waiver Program.) are included.
- Permit handling: Confirm they manage San Antonio's permit process ("By right, no zoning hearing: file a Residential Building Permit in BuildSA (a combination permit covering building, electrical, mechanical and plumbing) with a site plan, foundation plan, IECC energy report and Manual J/S HVAC sizing, plus proof that the owner-occupancy affidavit and covenant are recorded with Bexar County (IB 402; DSD ADU page). One of the five city Casita Permit-Ready Plans can serve as the building plans.", typically DSD publishes only its review targets: up to 3 business days for intake/completeness review and up to 3 business days for the first plan-review redlines; the permit issues once corrections are accepted and fees paid (DSD ADU page; DSD fact sheet 3/28/2023). Total time to permit is not published.) and who is responsible if revisions are required.
- Payment schedule: Avoid large upfront payments. A reasonable schedule ties payments to completed milestones.
Questions to Ask Before You Hire
- How many ADUs have you built in San Antonio in the last two years?
- Is your bid fixed-price, and what would trigger a change order?
- Are permits, plan check, and utility connection fees included?
- What's a realistic timeline, including permit review (DSD publishes only its review targets: up to 3 business days for intake/completeness review and up to 3 business days for the first plan-review redlines; the permit issues once corrections are accepted and fees paid (DSD ADU page; DSD fact sheet 3/28/2023). Total time to permit is not published.) and construction?
- Who is my point of contact and how are delays communicated?
- What warranty do you provide on workmanship?
- Can you share three recent Texas ADU client references?
Finance Your ADU Project
Most ADU projects are funded through HELOCs, construction loans, or cash-out refinancing. Compare rates from top lenders.
Some links on this page are affiliate links. We may earn a commission at no extra cost to you. Learn more
Are you an ADU builder? Get San Antonio leads
Homeowners on this page submit real ADU project requests in San Antonio. Each one goes to up to five local builders — that is what the homeowner agrees to — so claiming never takes it from anyone and there is no bidding. In practice far fewer ever make contact, which is why the number is five rather than three. A flat $50 only on the leads you accept: no subscription, no contract, and you deal with the homeowner directly.
Get San Antonio ADU Leads →Frequently Asked Questions
How much do ADU builders charge in San Antonio?
How do I find a good ADU builder in San Antonio?
Do ADU builders in San Antonio handle permits?
How long does it take to build an ADU in San Antonio?
Get Free ADU Builder Quotes in San Antonio
Compare bids from experienced local San Antonio ADU builders. Free, no obligation.
Get Free Quotes →